As a drive source of an electric tool for driving an end tool, an electric motor using AC power is widely used, as disclosed in JP-A-2011-148069. In the case of the electric motor using the AC power, compared to an electric tool using a DC motor with a battery, an output is high, and further, a long time operation is possible. On the other hand, when using the AC power, it is required to connect a power supply cord to a socket. Accordingly, available locations may be limited, compared to a portable electric tool with a battery. When the electric tool using the AC power is used in a location with no socket, an extension cord 104 wound around a cord reel 103 is often used to supply power from a socket 105 to an electric tool 101, as shown in FIG. 10. In this case, the cord reel 103 is placed within a range where a power supply cord 102 extending from the electric tool 101 can be connected. When observing an actual using site, the extension cord 104 having a length of approximately 100 m or more is often used.